The objective of this application is to investigate how the mechanical and anatomical (geometrical) structure of the Eustachian tube (ET) affects its ability to regulate Middle Ear (ME) pressure. Normally, this function is achieved by the intermittent opening of the ET due to the contraction of the surrounding musculature. Clinical and experimental studies have demonstrated that disruption of this opening mechanism results in one of the most common childhood diseases, otitis media with effusion (OME), and the associated hearing impairment. To obtain a fundamental understanding of the ET structure-function relationship, we propose to create a computational model that is capable of simulating both mechanical and anatomical variations. This model will be used to perform detailed simulations of ET opening phenomena during swallowing under various mechanical and anatomical conditions. As such, this work will elucidate how the interaction between mechanical and anatomical properties affects ET function. In addition, experimentally measured structural properties from normal adults will be incorporated into the model to obtain a better understanding of the "normal" ET structure-function relationship. The specific aims of this project are: 1) Develop a 2D computational model to investigate the influence of structural properties on ET opening phenomena during swallowing; 2) Develop and compare a 3D reconstructed mode of the ET with a 2D approximation to determine the importance of 3D geometrical variations; 3) Utilize the computational model to investigate and quantify ET opening phenomena in normal adults. The proposed work will elucidate how the mechanical and anatomical properties of the ET influence opening phenomena. In addition, we will establish normative data on the ET's mechanical and anatomical structure. This information is vital to the long term goal of this research which is to develop effective treatment strategies based upon the underlying structural deficiencies for persistent OME. Further, the results of the proposed research will provide the basic data which can be used as a comparative database for future studies that will quantify the ET structure-function relationship in OME patients, evaluate computationally various clinical therapies, and develop refined computational and/or experimental models.